Evolution
Vocabulary—Yes!!
1.
2.
3.
4.
5.
6.
7.
8.
9.
Evolution
10. Population genetics 19. Sexual selection
Natural selection
11. Microevolution
20. Stabilizing selection
Adaptation
12. Bell curve
21. Disruptive selection
Fitness
13. Gene pool
22. Directional selection
Convergent evolution 14. Allele frequency
23. Speciation
Divergent evolution 15. Phenotype frequency 24. Geographic isolation
Adaptive radiation 16. Hardy-Weinberg
25. Allopatric speciation
Genetic Equilibrium 26. Reproductive
Artificial selection
17. Gene flow
isolation
Coevolution
18. Genetic drift
27. Sympatric speciation
History of Evolution
• Originally most scientists believed species were permanent and
unchanging
• With the discovery of fossils of unique organisms, CATASTOPHISM,
was a theory that sudden geologic changes caused extinction of large
groups of organisms.
• Jean Baptiste Lamarck came up with an early idea of evolution, that
individuals could acquire traits during their lifetimes and pass those
traits on to offspring
Charles Darwin
•Darwin spent years traveling the globe
and making detailed observations to
develop the theory of NATURAL
SELECTION.
•Brainpop! Charles Darwin
•Darwin’s Finches Activity
Fill in the missing boxes. Food Choices: Fruit, Cactus, Seeds, Insects
Instagrammin Darwin!
Natural Selection
• Natural Selection= the mechanism (the ‘how’)
for descent with modification. Basically,
organisms best suited for an environment will
survive to pass on their traits to their offspring.
Organisms lacking traits to make them successful
will die and therefore not be able to pass on the
unsuccessful traits.
Evolution and Selection POGIL
4 Parts of Natural Selection
Overproduction
Genetic
Variation
Struggle to
Survive
Differential
Reproduction
Overproduction
•Species produce more individuals than
will survive to maturity
•The environment will limit the number
of individuals that reach adulthood
Genetic Variation
•Individuals of a population differ in
traits such as size, color, strength,
speed, ability to find food,
resistance to disease
Struggle to Survive
• Individuals within a population must compete
with each other for limited resources (food,
shelter, etc).
• A trait that makes an individual successful in its
environment (thick fur in cold climates) is called
an ADAPTATION.
• Giraffe Video Clip
Differential Reproduction
• Organisms with the best adaptations are the most
likely to survive and therefore pass on those
successful adaptations to offspring
• Through inheritance the adaptations will become
more frequent in the population
• The environment, ‘selects’, the most favorable traits =
NATURAL SELECTION
• Natural Selection Crash Course
Survival of the Fittest
•Fitness is a measure of an individual’s
hereditary contribution to the next
generation.
•A ‘fit’ individual is one that has offspring
that live long enough to also reproduce.
•Lion Fitness Activity
Darwin and Wallace
Modeling Natural Selection
• Bird Beak Lab with write up
• Battle of the Bird Beaks!
Types of Evolution
• CONVERGENT EVOLUTION: The process by which
different species evolve similar traits.
• The anole lizard evolved on 2 separate islands
from 2 distinct ancestors, but since each species
had similar habitats they both evolved with
similar twig-dwelling traits, but remain 2
separate species.
Types of Evolution
• DIVERGENT EVOLUTION: process in which
descendants of a single ancestor diversify into
separate species that fit different environments
• ADAPTIVE EVOLUTION: a new population will
evolve traits to fit its new environment
Adaptations in Action
Choose one of the above animals (or think of your own). On one side of the
paper draw the animal in its environment today. On the other side of the
environment draw the animal in 10,000 years—change the environment in
some way and label the adaptations the animal evolved.
Population Genetics
• The study of evolution from a genetic point of view
• Variation of traits within a population can be shown on a bell curve,
with most organisms falling in the middle range
Causes of Genetic Variation
•Environmental factors
•Heredity
•Mutation
•Recombination
The Gene Pool
• The GENE POOL = the total genetic information
available in a population (all of the possible alleles)
• ALLELE FREQUENCY= the specific allele (A or a)
divided by the total number of alleles in the
population
• PHENOTYPE FREQUENCY= the specific phenotype (Red
or Pink) divided by the total number of organisms
• Flower Color Activity
Hardy-Weinberg Genetic Equilibrium
• Genotype frequencies in a population tend to remain
the same from generation to generation unless acted
upon by an outside influence.
• Ideal population in Hardy-Weinberg Equilibrium:
1.
2.
3.
4.
5.
No mutations occur
No individuals enter or leave the population
The population is large
Individuals mate randomly
Natural Selection does not occur
Disruption of Genetic Equilibrium
• Mutation
• Gene Flow—immigration and emigration
• Genetic Drift—allele frequencies change as a result of
random events, leading to a particular allele (A or a)
disappearing completely and thereby reducing genetic
variation. GENETIC DRIFT is only significant in small
populations
• Nonrandom Mating—Sexual selection
• Natural Selection—stabilizing, disruptive, directional
selection
Population Genetics Crash Course
• Honors: Hardy-Weinberg Practice!
• Regular: Review Sheet
Formation of Species
•SPECIATION is the process of the formation
of a new species.
•A species is a group of organisms that can
successfully interbreed (and the offspring
can also reproduce) and have similar
morphological (internal and external
structures) features.
Isolation and Speciation
•Geographic (allopatric) Isolationpopulations become physically separated
(canyon, river,mountains) and gene flow
between the 2 groups stops. Natural
selection and genetic drift then make the 2
groups incompatible for mating and the 2
groups evolve separately.
Isolation and Speciation
•Reproductive (sympatric) Isolation– barriers
to successful breeding between 2
populations. Examples: different mating
times, different mating calls
Speciation Video Clips
• Geographic Separation
• Speciation Crash Course
Speciation Activity
Design a creature and show how one creature evolves into 2 species
because of geographic isolation. Draw your two new species and list
the traits/adaptations that make it unique.
Review
• Evolution Concept Map
• Study Guide